Apple CEO Tim Cook talked about a lot of things as he made his second appearance at the annual D: All Things D conference. Come to think of it, it may be more factual to say that he did not talk about a lot of things, particularly those pertaining to Apple's upcoming products, rumored or otherwise. But he did make an announcement concerning Apple's important new hire.
During his interview with Walt Mossberg and Kara Swisher at the D11 conference, Cook announced that Lisa Jackson will be joining Apple. Jackson, who served as the Administrator of the Environmental Protection Agency (EPA) from 2009 to 2013, will become Apple's top environmental adviser.
As noted by AllThingsD:

Jackson left the EPA at the end of 2012, after a four-year term in office, aiming to enact large-scale changes to address climate change and other problems with the environment on a national and global level.
But Jackson’s tenure was cut short as she stepped down amid a secretive email scandal, in which she admitted to conducting official private EPA business under a false email alias.

In a statement to The Washington Post, Jackson said, "I’m incredibly impressed with Apple’s commitment to the environment and I’m thrilled to be joining the team."
One of the most recent developments to come out of this commitment is Apple's successful move to run its data centers using 100 percent renewable power. This move came as a positive response to an outcry from Greenpeace last year, which criticized Apple for using "dirty" or nonrenewable energy to power its iCloud data center in Maiden, North Carolina.